A systematic review of match-play characteristics in women’s soccer

This review aimed to (1) systematically review the scientific literature evaluating the match-play characteristics of women’s soccer, (2) determine the methods adopted to quantify match-play characteristics of women’s soccer, and (3) present the physical, technical and tactical characteristics of women’s soccer match-play across age-groups, playing standards and playing positions. A systematic search of electronic databases was conducted in May 2021; keywords relating to the population, soccer and match-play characteristics were used. Studies which quantified physical, technical or tactical performance of women’s soccer players during match-play were included. Excluded studies included adapted match-play formats and training studies. Sixty-nine studies met the eligibility criteria. Studies predominantly quantified match-play characteristics of senior international (n = 27) and domestic (n = 30) women’s soccer match-play, with only seven studies reporting youth match-play characteristics. Physical (n = 47), technical (n = 26) and tactical characteristics (n = 2) were reported as whole-match (n = 65), half-match (n = 21), segmental (n = 17) or peak (n = 8) characteristics. Beyond age-groups, playing standard, and playing position, fourteen studies quantified the impact of contextual factors, such as environment or match outcome, on match-play characteristics. Distance was the most commonly reported variable (n = 43), as outfield women’s soccer players covered a total distance of 5480–11160 m during match-play. This systematic review highlights that physical match-performance increases between age-groups and playing standards, and differs between playing positions. However, further research is warranted to understand potential differences in technical and tactical match-performance. Coaches and practitioners can use the evidence presented within this review to inform population-specific practices, however, they should be mindful of important methodological limitations within the literature (e.g. inconsistent velocity and acceleration/deceleration thresholds). Future research should attempt to integrate physical, technical and tactical characteristics as opposed to quantifying characteristics in isolation, to gain a deeper and more holistic insight into match-performance.


Introduction
There has been substantial global growth and development of women's soccer within recent years. Global, continental and national governing bodies have implemented specific women's soccer strategies and increased investment, to support the development of the sport from grassroots to elite playing standards [1][2][3][4][5]. There has been an increase in participation rates [3], increased provision and support for developing talented youth players (e.g. the English Football Association's regional talent centres and Women's Super League academies programme), increased professionalisation of elite playing standards [6], and subsequently increased audiences for elite senior competitions (e.g. FIFA Women's World Cup, UEFA Women's European Championships, UEFA Champions League) [3,5,6]. Furthermore, recent research has suggested that observed increases in physical match-play performances of elite senior players are consequential of the sport's growth and development, and increased professionalisation of the game [7,8].
Additionally, there has been a notable increase in the volume of literature focusing on women's soccer [9], which is likely reflective of the sport's growth and development. The focus of the literature to date has predominantly surrounded injury and strength and conditioning of women's soccer players, with limited research quantifying the match-characteristics of women's soccer [9]. This is problematic, as knowledge and understanding of the demands which players may experience during match-play is important for informing population-specific practices for match-play and beyond. For example, coaching practice design and training programme design in preparation for the demands of match-play within respective playing standards, preparing players transitioning across playing standards, long-term athletic player development practices, talent identification, or injury monitoring and rehabilitation processes.
Despite a relatively limited body of literature, there have previously been six narrative reviews summarising match-play characteristics of women's soccer [10][11][12][13][14][15]. However, there are several important limitations associated with these reviews. Firstly, without a comprehensive literature search and pre-defined, objective study selection criteria, narrative reviews may involve subjective study selection bias [16]. Additionally, the depth of information or choice of data extracted from respective studies may be limited or subjective. Consequentially, narrative reviews may result in biased or subjective author interpretation and conclusions [16]. Therefore, there is a need for a systematic review, to provide a comprehensive, objective and scientifically rigorous summary of the evidence-base on match-play characteristics of women's soccer. Secondly, all narrative reviews to date have exclusively summarised the physical characteristics of match-play, neglecting the important technical and tactical characteristics. This is problematic, as soccer performance is the combination of physical, technical and tactical characteristics, and thus aspects of performance should not be considered in isolation [17,18]. Therefore, there is a need to review and summarise physical, technical and tactical characteristics, to provide a holistic understanding of women's soccer match-play. Thirdly, narrative reviews have highlighted methodological inconsistencies within the literature (e.g. methods of data collection, and velocity or acceleration thresholds). However, no review has attempted to evaluate the methodologies adopted to quantify match-play characteristics. Methods of data collection within recent research likely differ compared to earlier studies, due to FIFA law changes permitting wearable technology (e.g. global positioning system (GPS) units) within competitive match-play. Therefore, it is important that researchers and practitioners have an awareness and understanding of the different methodologies utilised within the literature when interpreting match-play characteristics and informing research or practice. Lastly, existing reviews neglected to summarise the peak periods of women's soccer match-play characteristics [19,20], which provide insight into the worst-case scenarios players may face during

Methodological quality
The methodological quality of the selected studies were assessed in line with previous systematic reviews involving match performance of soccer players [22,23]. The methodological quality criteria are shown in Table 1. A maximum score of 10 out of 9 criteria questions could be obtained. Where 'clearly' is included within criteria, this required the relevant information to be explicitly detailed within the study. Methodological quality was included for descriptive purposes as opposed to criteria for inclusion/exclusion within this review.

Data extraction
Data were extracted by one author (AHA), and checked by a second (NM), with any disagreements resolved through discussion. Data relating to participant and study characteristics (e.g. age, height, body mass, standard of competition, number of teams, number of matches), methods of data collection and analysis (e.g. equipment specification, adopted velocity thresholds, variable definitions), and match-play characteristics (e.g. physical, technical or tactical variables, and match contextual information such as match outcome) were extracted. Where data were presented as figures, WebPlotDigitizer v4.4 [24] was utilised to extract data. Where studies included other data in addition to the relevant data, only the eligible data relating to matchplay characteristics of women's soccer players were extracted. For example, sex-differences [25][26][27][28][29][30], training and adapted match-formats [29,[31][32][33], matches against men's soccer teams [34], or assessments of fitness or physiological characteristics [35,36]. Lastly, to facilitate comparisons between studies, metrics were converted to standard units, including; player height (cm), distance covered (m), and relative distance covered (m�min -1 ).

Statistical analysis
A meta-analysis was precluded within this systematic review due to the variation in methods of data collection and analysis. Data are presented as mean ± SD. Where possible, any data extracted as mean ± SE or confidence intervals were converted to SD [19,[37][38][39][40][41][42], however, where this was not possible due to insufficient methodological information provided within studies, SE or confidence intervals were reported and noted [8,26,33,[43][44][45][46]. Table 1. Methodological quality criteria for selected studies.

Question
No.

Q1
The study is published in a peer-reviewed journal No = 0, yes = 1

Q2
The study is published in an indexed journal No = 0, yes = 1

Q3
The study objective(s) is/are clearly set out No = 0, yes = 1

Q4
Either the number of recordings is specified or the distribution of players/recordings used is known The duration of player recordings (an entire half, a complete match etc.) is clearly indicated.
No = 0, yes = 1 Q6 A distinction is made according to player positions No = 0, yes = 1

Q7
The reliability/validity of the instrument is not stated, is mentioned or is measured Not stated = 0, mentioned = 1, measured = 2

Overview
Fig 1 presents a flow diagram of the study selection process. The electronic database search identified 1562 articles, with an additional 29 articles identified through other sources. A total of 69 articles remained for analysis following removal of duplicates, initial and full-text screening [8,19,20,.

Discussion
This is the first systematic review to summarise women's soccer match-play, including the technical, tactical and physical characteristics. A total of 69 studies were included, predominantly quantifying physical characteristics (68%), whilst 38% quantified technical characteristics, and only 3% quantified tactical characteristics. Studies reported whole-, half-, segmental and/or peak match characteristics for physical data, however studies reporting technical and tactical characteristics were predominantly limited to whole-match analysis. There has been an increase in the number of studies quantifying women's soccer match-play characteristics in recent years, however, studies predominantly involved senior international (39%) and domestic players (43%), with only 10% quantifying match-play characteristics of youth (age-group) soccer players. Physical characteristics appear to increase between age-groups and playing standards, and are dependent upon playing position. Furthermore, there are between-half decrements in physical performance, with the opening 15-minutes of match-play the most physically demanding. Further research quantifying the technical and tactical characteristics is required to understand differences within and between age-groups and playing standards. The results of this review provide insight into the current match-play characteristics across different playing standards and playing positions, which will be beneficial for researchers and practitioners implementing evidence-based practice with women's soccer players.

Methodologies for quantifying match-play characteristics
There are important methodological limitations to acknowledge when interpreting and comparing the extracted data. Firstly, over half of the included studies which reported number of teams involved only a single-team or single-club. This is problematic, as results may not be reflective of the population due to individual team/club strategies, tactics or playing styles, which may influence players' physical, technical and tactical performance. Future research should adopt multi-club data collection approaches to overcome this issue. Secondly, positional categorisation was inconsistent, which may be a consequence of small sample size within studies. Only nine of the twenty-six studies [8,19,26,33,37,51,52,74,80] quantifying position-specific characteristics differentiated both central and wide defenders and midfielders. High-level positional categorisations (i.e. defender or midfielder) may not provide accurate insights into match-play characteristics, given the positional differences observed when central and wide players are compared [19,37,51,74]. Thus, in addition to adopting a multi-club approach, future research should ensure sufficient sample size (participants and match observations) to differentiate central and wide playing-positions. Thirdly, comparing physical characteristics quantified by different equipment requires caution due to between-system differences (i.e., video-based time-motion analyses vs GPS units vs optical tracking; 5 vs 10 vs 15 Hz GPS) [91][92][93][94]. Furthermore, where studies have adopted the same data collection method (e.g. 10 Hz GPS units), differences exist between manufacturers' hardware, firmware, data filtering and data processing methods [95,96]. Therefore, direct comparison of findings between studies adopting different data collection methods may not be appropriate, and this further limits the potential insights which can be gained regarding the physical characteristics.
Lastly, a range of velocity and acceleration/deceleration thresholds have been adopted, with methods for establishing or adopting thresholds also differing between studies (e.g. arbitrary thresholds within men's soccer, derived from physical performance characteristics, derived from match-play data of senior women's soccer players). This has resulted in varying velocity and acceleration/deceleration zones, impacting comparisons between studies. There is a need for future research to establish a standardised approach for adopting velocity and acceleration/ deceleration thresholds within women's soccer to facilitate comparisons between studies. However, practitioners and researchers should also have an awareness and understanding of the potential impact thresholds may have on physical characteristics. For example, recent research found adopting senior-derived velocity thresholds for youth match-play, resulted in an underestimation of higher-speed distances as senior-derived thresholds are too excessive to accurately reflect the physical characteristics of youth players [97]. In this instance, adoption of senior-derived velocity thresholds may lead to misleading data and subsequently erroneous interpretations of the physical characteristics of youth match-play. Therefore, we recommended that researchers and practitioners make an informed-decision, depending upon their

PLOS ONE
study aim or intended use of the data, as to whether it may be more appropriate to adopt senior-derived velocity thresholds or population-specific velocity thresholds. The underpinning methodological limitations within the body of literature limits the insights which can be gained across women's soccer populations. Consequently, researchers and practitioners using the match-play characteristics presented within this review, particularly the physical characteristics should be cautious in their interpretation and application of the data. Furthermore, subsequent discussion within this systematic review, is reflective of the limitations highlighted.

Absolute technical characteristics.
There were consistent findings in technical characteristics across studies. Unsurprisingly, passes were the most frequent technical action in possession across playing standards, with an increasing pass success rate from youth (63-65%) [37] to senior match-play (67-80%) [26,27,31,50,55,67,76]. Tackles and interceptions were the most common defensive actions in senior and youth match-play [27,31,37,55]. However, given the limited number of technical characteristics quantified across studies, it is difficult to explore potential differences in playing styles across playing standards. Additionally, the technical data presents on-the-ball technical actions for both in-possession (e.g. passing, crosses, or shots) and out-of-possession (e.g. clearances, interceptions, or tackles), which can be useful for practitioners informing coaching practice. However, given the small duration of time spent on the ball (senior = 67 ± 3 s; youth = 32-35 s) [26,37] and low frequency of these technical actions, future research should aim to quantify off-the-ball technical actions, technical-tactical or physical-technical actions [17], such as pressing, pass effectiveness or sequences/patterns of play [47,83], to gain better understanding of technical performance.

Absolute tactical characteristics.
Tactical characteristics referred to players' positioning which provide insight to teams' playing length and width, and players' individual playing area, dependent upon ball location [30,90]. The data presented may help practitioners determine appropriate dimensions for training drills, conditioned or small-sided games. However, the reported data lacks physical, technical and situational context. Therefore, further research is required to better understand team behaviours, and how physical and technical characteristics may interact with tactical strategies [27,28,68]. Furthermore, tactical characteristics are often dynamic, thus future research should aim to improve our understanding of the tactical characteristics across match-play, or prior-to and following key moments in matchplay, and how contextual factors (e.g. match status) may affect tactical performance. However, it is important to acknowledge the challenges and complexities associated with this research and within practice [98,99]. For instance, collecting sufficient data for appropriate analyses, the advanced theoretical and computational underpinning knowledge required for analyses, ability to work with complex datasets, and multidisciplinary collaboration. We anticipate that as the involvement of big data technologies within the women's game increases, and more commercial data providers provide readily-available access to physical and technical data [53,55], the body of literature exploring tactical characteristics in senior international and professional playing standards will grow accordingly.

Position-specific absolute characteristics.
Senior goalkeepers cover 4445-5622 m during match-play [8,62,74], predominantly at lower speeds. Unsurprisingly, goalkeepers covered less TD, HSR, VHSR and SPR distances, than outfield players. However, given the different movements and technical-tactical skills associated with goalkeeping, position-specific characteristics (e.g. number, intensity, and direction of movements such as diving, jumping or kicking) [100] would be more appropriate than distances covered. Future research should aim to improve our very limited understanding of women's soccer goalkeeper match-play characteristics, to help inform goalkeeper-specific training and coaching practice.
When studies differentiated central and wide players, central defenders typically covered the lowest TD, HSR, VHSR, and SPR distances [8,19,20,26,51,70,74,78,79], performed the least HSR and SPR efforts [20,52,73], and had the least total and average duration of possession, touches per possession, and offensive touches during youth match-play [37]. Central midfielders covered the most TD [8,19,26,51,62,74], and had the lowest maximum velocity [8,19]. Furthermore, Harkness-Armstrong et al. [37] reported central midfielders had the greatest active involvement in youth match-play with the most offensive touches and passes, as well as the most tackles. Considering HSR distance, three studies reported wide midfielders covered the most [8,19,74], whilst Bradley et al. [26] and Datson et al. [51] reported forwards and central midfielders covered the most, respectively. Forwards and wide midfielders consistently covered the most VHSR and SPR distances [8,19,51,74], and attempted the most dribbles, crosses and shots during youth match-play [37]. There was a discrepancy in position-specific accelerations and decelerations between studies, however this may be due to respective samples adopting notably different acceleration and/or deceleration thresholds. Although comparison of physical and technical characteristics are limited due to methodological differences, clear differences exist between playing positions and the data reported within the current review can be used to inform position-specific training drills and coaching practice to prepare players accordingly for match-play.
Quantifying relative characteristics normalises data to minutes played, removing potential differences in data due to match-duration across match observations, which is particularly useful for comparisons between groups, especially age-groups with differing match durations [19]. However, it is important to acknowledge that relative whole-match data includes ball out of play time, which has been found to be between 38.0 and 41.6% of the time in women's soccer [37,51]. Whilst inclusion of ball out of play time has been found to underestimate physical characteristics in men's soccer populations [101,102], the effect on women's soccer players is yet to be quantified. Therefore, future research across women's soccer populations should explore the differences between ball in play and whole-match characteristics, to better understand the physical and technical characteristics, and to ensure practitioners can implement coaching practice and training drills which better represent match-play demands.

Influence of contextual factors.
Excluding playing standard, age-group and playing position, only fourteen studies [36,38,46,49,50,55,63,67,68,71,76,83,84,89] quantified the influence of contextual factors on match-play characteristics. Studies predominantly reported whole-match characteristics, with physical characteristics primarily presented as relative values. Whereas technical data were either presented as absolute or relative to match duration, which may lead to erroneous interpretation when comparing the effect of contextual factors. For example, Póvoas et al. [76] found international low-ranking teams performed more successful tackles, recoveries and challenges than high-ranking teams. However, this may be due to low-ranking teams having less possession, and thus more opportunity to perform defensive actions than high-ranking teams. Therefore, future research should present possession-dependent technical characteristics relative to possession status [37]. Additionally, studies quantified contextual factors in isolation (i.e. match location, match congestion, or opposition quality), with only Trewin et al. [84] combining contextual factors (i.e. match outcome and opposition quality; win vs higher ranked opponent). Quantifying contextual factors in isolation may be consequential of limited sample size or match observations. However, caution should be taken when interpreting the influence of isolated contextual factors given the complex, multifaceted nature of match-play performances [103].
Acknowledging these limitations; high temperatures [36,84], altitude [49,84], match congestion (<42h) [71,84], playing against lower ranked opposition [38,84], playing on grass rather than artificial turf [46], in-conference matches as opposed to out-of-conference fixtures (type of competition) [50], and competing in matches post-season compared to regular-season (seasonal changes) [89], resulted in reduced physical characteristics. However, all studies were conducted with a single-team, thus further research with a multi-club approach, larger sample size and greater number of match observations is required to identify whether these findings are generalizable to the wider women's soccer population. Four studies quantified match characteristics according to match outcome [46,67,83,84]. Differences in physical and technical performances were observed in teams who won, drew or lost across studies, however caution should be taken when interpreting this data. Grouping match observations by match outcome can be an overly-simplistic approach, which does not reflect the fluidity of match status during observations, and may subsequently lead to erroneous categorisation. For example, a team may score within the final minutes of match-play after drawing for the majority of the match, yet be categorised as a win. Therefore, we recommend future research explores the influence of match status (i.e. drawing, winning or losing) as opposed to match outcome on match-play characteristics. Finally, one study [63] attempted to explore sex-specific considerations on match-play performance. The authors compared physical characteristics during match-play between the follicular and luteal phase of the menstrual cycle. However, due to the complexities of data collection (e.g. small sample size due to strict participant inclusion criteria, individual and match-to-match variability) the authors could not attribute changes in performance to the menstrual cycle. Whilst there are considerable complexities to conducting such research [104], further work is warranted to explore the influence of sex-specific considerations on match-play performances.
Interestingly, alongside the observed reductions in physical performances, senior domestic players had less individual time in possession in the second half (-7.8%; 34.6s vs 31.9s) [26]. The remaining technical characteristics show similar technical performances between-halves. However, only a small number of technical characteristics were quantified, which were predominantly infrequent on-the-ball technical actions (e.g. duels, headers and tackles) [26,44], therefore limited insight can be gained as to potential differences in technical performances between-halves. Additionally, no position-specific technical characteristics were quantified which is problematic, as player averages may provide limited insight into technical performances, given that technical characteristics differ between positions for whole-match [37,55,88]. Furthermore, position-specific differences and between-half decrements were observed in physical half-match characteristics [26,74,77]. Therefore, future research across playing standards should aim to quantify half-match physical, technical and tactical characteristics according to playing position. This information will enable practitioners to design and deliver position-specific practices to prepare players for match-play and improve their ability to sustain performances between-halves.
The observed reductions in physical characteristics across match-play (half-match and segmental), may be consequential of reduced physical performance capacities due to physical fatigue, pacing strategies, or an increased perception of effort due to mental fatigue [18,44,66]. Furthermore, technical-tactical performance, situational and contextual variables may also contribute to these reductions, however physical characteristics have predominantly been quantified in isolation. Thus, future research should aim to quantify technical and tactical characteristics alongside physical characteristics, as well as exploring the influence of situational and contextual factors, to understand their influence in reductions in physical performance across match-play. For example, playing styles, team strategies or formation may differ over the duration of match-play but also in response to match status [105], substitution strategies influence on observed players' physical characteristics [106,107], or whether ball-in play time differs across the match and thus influences physical performances [96,108]. This information would be important for practitioners when informing technical-tactical drills or conditioned games to prepare players for the fluctuating demands of the game, or training prescription which aims to increase players' physical capabilities to sustain physical performances throughout match-play, but also for informing tactical coaching interventions during match-play.

Peak characteristics
All eight studies reporting peak characteristics, quantified physical characteristics for a 5-minute period [19,20,26,43,44,51,74,78]. TD covered appeared to increase with increasing playing standards [19,20,74,78]. However, comparison of HSR, VHSR and SPR distances and number of accelerations and decelerations, during peak-periods is limited, given the different methods adopted across the eight studies (e.g. five HSR velocity thresholds, three accelerations/ decelerations thresholds). Furthermore, two studies [19,20] quantified peak periods by a moving-averages approach, whilst the remaining studies adopted a pre-determined segmental analysis approach. Previous research within other sporting populations (e.g. men's soccer, men's rugby union) found adopting segmental periods can underestimate peak TD and HSR distances by up to 25% in comparison to moving average analysis [109][110][111][112]. Therefore, it is likely peak-data quantified via segmental analysis [26,43,44,51,74,78] underestimates the peak characteristics of women's soccer players. Therefore, it is not possible to determine whether differences across playing standards is reflective of the increased demands, or a consequence of different methods. Thus, practitioners utilising peak data to inform coaching practice and training programme design to prepare players for the worst-case scenarios in match-play should be aware of the methods of analysis adopted. Furthermore, future research should adopt a moving average analysis when quantifying peak periods of women's soccer.
Only one study [19] quantified peak periods at differing durations (1-10 minutes), and observed youth players covered the greatest distances during the 1-minute period, whilst relative distances reduced as duration increased, with the least distances covered during the 10-minute period. This is consistent with previous research in men's soccer [110,111]. Whilst underlying reasons why this reduction may occur is not known (e.g. reduction in physiological capacity; differing technical-tactical demands between peak periods) [96], duration-specific peak characteristics can be used to inform duration-specific training programme design or coaching practice. However, it is not appropriate to inform duration-specific training drills when duration-specific data does not align (i.e. 5-minute data to inform 3-minute training drills) [110]. This is problematic, as only 5-minute peak periods have been quantified for senior populations. Therefore, future research should quantify peak characteristics of 1-10-minute durations, to understand the duration-specific worst case scenarios within senior match-play, which can be used to inform duration-specific practices to optimally prepare players for the most physically demanding periods of match-play.
Four studies [19,20,74,78] quantified position-specific peak physical characteristics. During 5-minute peak periods, central defenders typically covered the least TD [19,20,74], and HSR distance [19,20,74,78], whilst central defenders and central midfielders covered the least VHSR [19,74], and SPR [74,78] distances. Where studies differentiated central and wide defenders and midfielders [19,74], central midfielders covered the greatest TD, and wide midfielders covered the greatest HSR, VHSR and SPR distances. Furthermore, Harkness-Armstrong et al. [19] reported position-specific differences in TD, HSR and VHSR across 1-10 minute peak durations. The data indicates that peak physical characteristics are positiondependent, thus practitioners should implement position-specific practices to prepare players accordingly for the varying worst case scenarios in match-play. Additionally, the data highlights the need for research to quantify peak characteristics beyond TD (e.g. distances in velocity zones, number of accelerations) to facilitate position-specific differentiation of specific worst-case scenarios.
Consistent with other areas within this review, peak characteristics have quantified physical characteristics in isolation, which provides limited insight into the true demands and context of these worst-case scenarios within match-play [17]. Additionally, recent research in elite men's soccer [113] found physical peak characteristics lack context due to the multifaceted nature of worst case scenarios, which consequently results in high variability. Therefore, future research should; quantify the associated technical and tactical characteristics during peak physical periods, to understand how technical-tactical roles may influence worst case scenarios; attempt to quantify the peak technical and tactical periods of match-play and the associated physical characteristics; explore how contextual factors (e.g. match status, formation, opposition quality, ball possession) influence worst case scenarios [111,114], and quantify the variability of peak characteristics in women's soccer match-play. As previously discussed, attempting to integrate the physical, technical and tactical characteristics, and understand the variation within and between matches will provide greater insight into these worst-case scenarios, and enable evidence-informed design and prescription of coaching practice and training programmes to optimally prepare players for the most demanding periods of match-play.

Limitations
This review has presented study limitations throughout, and the caution required when interpreting results or informing practical applications. For example, this review has identified key methodological limitations within the literature which limits comparisons between studies, including; single-team samples; differing data collection methods; and no standardised velocity and acceleration/deceleration thresholds. Consequently, researchers and practitioners should be cautious in their interpretation of the reported data, whilst future research requires greater consistency in the methods adopted to facilitate comparisons between studies. For example, multi-club samples to ensure findings are generalizable to the population, positionalcategorisation of players which differentiate central and wide players as opposed to high-level categorisation (i.e. defenders vs midfielders vs forwards), and to establish and adopt standardised velocity, acceleration and deceleration thresholds/zones for women's soccer, to facilitate comparisons between and within playing standards.
The heterogeneity of the included studies' samples and methodologies prevented the inclusion of a meta-analyses within the current systematic review. Given the extent of the current review in summarising all physical, technical, and tactical characteristics during match-play, across all playing standards of women's soccer, there is a very large breadth of results which may be overwhelming. However, given the recent growth, development, and investment within women's soccer, the authors strongly believe there is a timely need for the current review; to collate all current evidence regarding women's soccer match-play characteristics, and provide practitioners with a critical resource which can be utilised to develop evidenceinformed practice within women's soccer populations.

Conclusions
The quantification and understanding of match-play characteristics is important for informing practices across women's soccer populations. This is the first systematic review to summarise the scientific literature evaluating the match-play characteristics of women's soccer, and presents the physical, technical and tactical characteristics of women's soccer match-play across age-groups, playing standards and playing positions. Furthermore, this review provides a critical evidence-based resource which can be used to inform population-specific practices across women's soccer playing standards.
The current review has identified that physical characteristics appear to increase between playing standards and differ between playing positions. Furthermore, between-half reductions in physical characteristics were apparent, whilst the opening 15-minutes of match-play was consistently the most physically demanding. Additionally, peak physical characteristics were primarily quantified via a segmental analysis, which may underestimate the true worst-case scenarios of match-play. Therefore, research which quantifies the peak demands for differing durations via a moving-averages method is warranted across women's soccer playing standards. Additionally, further research is needed to understand technical and tactical characteristics of women's soccer match-play, and how performances may differ across playing standards. Furthermore, research should aim to integrate physical, technical and tactical characteristics rather than quantifying characteristics in isolation, to gain a holistic understanding of match-performance. In addition, further evidence is required regarding contextual factors within match-play, to understand how the characteristics players face during match-play may vary. Future research may also attempt to better our understanding of the match-to-match variation within women's soccer populations. As currently only two studies have quantified match-to-match variation of physical characteristics utilising single-team samples, this is therefore not generalizable to the wider population [20,72]. Finally, there is a heavy bias towards research quantifying match-play characteristics of senior players. The lack of research and subsequent knowledge and understanding of youth match-play characteristics (<U17) is problematic. Thus, further research is necessary within youth populations, to inform long-term talent development, transition of youth players across the talent pathway, and talent identification processes.